clarified colum name docs

removed unnecessary (and unhelpful) column name parameter from the
docs, instead documenting how to actually add a column name.

discovered through testing and clarified by @jacobmovingfwd and
@scottkawai in the Support Hipchat room
made email addition examples more readable

expanded curl call into a multiline statement for better readability
added a note about required fields

while this is documented in the parameter table, this is easy to miss
or misunderstand, this documents it a little further
Merge pull request #575 from nquinlan/lists

improved documentation around lists and adding columns & fields